This application is based upon and incorporates herein by reference Japanese Patent Application No. 2000-273584 filed on Sep. 8, 2000.
This invention relates to a method of producing a silicon carbide (SiC) device using a cleaned surface of a SiC substrate.
U.S. Pat. No. 6,214,107 discloses a method of cleaning a SiC substrate by etching process used in a silicon (Si) process. For example, buffered hydrofluoric acid process is used as follows. A surface of a SiC substrate is etched with a mixture solution of a hydrofluoric acid and an aqueous solution including ammonium fluoride of 40 vol.wt % (e.g., hydrofluoric acid:aqueous solution including ammonium fluoride of 40 vol.wt %=1:6).
In this method, however, carbon and the like in atmospheric air adhere to the surface of the SiC substrate while the SiC substrate is transferred. Actually, a composition on the surface of the SiC substrate obtained by this method is found to have a carbon cluster when analyzed by using X-ray photo electron spectroscopy (XPS).
The present invention has been made in view of the above problems. An object of the present invention is to prevent a cleaned surface of a Sic substrate from being contaminated by carbon and the like in atmospheric air so that a satisfactory SiC device can be produced.
According to the present invention, a SiC device is produced as follows. First, a silicon layer is formed on a surface of a Sic substrate. Then, the silicon layer is removed from the surface of the SiC substrate by supplying oxygen gas to the silicon layer in a high ambient temperature and a low oxygen pressure. The pressure is set at 1xc3x9710xe2x88x922 to 1xc3x9710xe2x88x926 Pa. Thus, contamination of the surface of the SiC substrate by carbon and the like in atmospheric air can be removed. Specifically, the silicon layer has 3xc3x973 surface structure, and the surface of the SiC substrate is cleaned to have 1xc3x971 surface structure.
Preferably, the oxygen pressure and temperature are set at about 10xe2x88x926 Pa and 1000xc2x0 C. for removing the silicon layer. Thereafter, the oxygen pressure is raised to about 104 Pa to form an oxide film on the silicon carbide film.